Miniature initiator assembly

ABSTRACT

A miniature initiator assembly which is adjusted to a selected one of several variable time delay settings immediately prior to use. A spool has an open end telescopingly received between the cartridge case and propellant container which are located in the initiator chamber, and the spool hub portion has a centrally located primer for actuation by a firing pin mechanism mounted in the initiator cap which is keyed to the spool and rotatably mounted relative to the initiator chamber. The cartridge case is keyed to both the chamber and container, the container having predeterminedly spaced sidewall ignition holes filled with igniter mix. An external spiral groove on the spool contains a pyrofuse cord and predeterminedly spaced lateral passages, with one end of the cord extending through one of the passages adjacent the primer. Relative rotation of the spool and container will enable a selected ignition hole to align with the cord to provide a desired effective length of the delay cords.

United States Patent [1 1 [in 3,762,267

Travor et al. 1 Oct. 2, 1973 MINIATURE INITIATOR ASSEMBLY Primary ExaminerSamuel W. Engle [75] Inventors: Bruce W. Travor, Holland, Pa.; Attorney-Harry saragov'tz et Lennord L. Pitney, Park Rapids,

Minn. ABSTRACT A miniature initiator assembly which is adjusted to a selected one of several variable time delay settings immediately prior to use. A spool has an open end telescopingly received between the cartridge case and pro- [22] Filed: June 26, 1972 pellant container which are located in the initiator 21 A l N 266 109 chamber, and the spool hub portion has a centrally lo- 1 pp cated primer for actuation by a firing pin mechanism mounted in the initiator cap which is keyed to the spool [73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[52] U8. Cl. 89/] B, 102/27 R, l02/85.2 and rotatably mounted relative to the initiator cham- [51] Int. Cl. F42c 9/00 h r. Th cartridge case is keyed to both the chamber [58] Field of Search 102/85.2, 27; 89/l; and container, the container having predeterminedly 42/1 spaced sidewall ignition holes filled with igniter mix.

An external spiral groove on the spool contains a pyro- [56] Referen es Cited fuse cord and predeterminedly spaced lateral passages, UNITED STATES PATENTS with one end of the cord extending through one of the 1,198,644 9/1916 Loomis 102/85.2 passages f" P Relatve i 'fi of the 3,453,959 7/1969 Hobart e! a] M l02/85'2 spool and container will enable a selected ignition hole to align with the cord to provide a desired effective length of the delay cords.

3 Claims, 2 Drawing Figures MINIATURE INITIATOR ASSEMBLY This invention relates to initiators, and more particularly, to time delay miniature initiators.

One of the objects of the invention is to provide a miniature initiator assembly having an improved variable time delay.

Another object of the invention is to provide such an initiator assembly having a rotary type adjustment for varying the cartridge time delay.

A further object of the invention is to provide such an initiator assembly that will require the minimum of cartridges for a propellant actuated device system having a variety of time delays.

These and other objects, features and advantages will become apparent from the following description and accompanying drawings in which: 7

FIG. 1 is a longitudinal sectional view of a preferred initiator embodying the principles of the invention.

FIG. 2 is an elevational view of the indexing spool in the FIG. 1 arrangement.

The initiator chamber 10 (FIG. 1) of the miniature initiator asembly has secured to its open end an initiator cap 11 by means of lock wire 12 which permits manual relative rotational movement therebetween as governed by the spring detent 13 on cap 11 snapping into consecutive equally and radially spaced appropriate openings 14in the chamber sidewall. Cartridge case 15 is longitudinally keyed (key 16 in keyway 17) to the initiator chamber 10, and the indent key 18 at the other end of the case 15 mates with the keyway 19 on the periphery of propellant container 20 to longitudinally key container 20 to case 15 adjacent O-ring seal 21. A substantial portion of the container 20 has a reduced diameter such that the annular portion of an open ended pyrofuze indexing spool 23 (FIGS. 1, 2) is telescopingly received in the annular space between the container and case 15. Suitable O-ring seals 24, 25, 26 are carried by the container 20, spool 23 and cap 11, respectively. Propellant container 20 has its sidewall provided with a plurality of longitudinally spaced ignition holes 28 which are filled with igniter mix and permitted to dry prior to loading of the propellant and igniter powder 29 and cementing of a nitrocellulose disc 30 as an open end closure upon assembly.

Spool 23 has an external spiral groove 31 extending a substantial portion of its length and terminating with an ignition chamber hole 32 at one end adjacent the primer 33 which is positioned centrally of the spool hub portion in alignment with the firing pin assembly 34 carried by initiator cap 11. A plurality of spool lateral passages 35 (FIG. 2) are provided at predeterminedly spaced locations along the groove 31 that contains the spirally wrapped braided pyrofuze cord 36. The cord 36 has a sufficient length to fill the groove 31 and pass through hole 32 with the uncovered pyrofuze end at least partially embedded in some igniter mix inside the spool adjacent primer 33. The spool lateral passages 35 preferably are spaced 1-1/6 revolutions along the groove such that the equal lengths of cord portions will produce available effective time delays of one-fourth second increments, depending on the selected rotational position of the spool through its opposed wingtype key and slot connections 38, 39 with the cap interior. The rotational position of the spool 23 and cap 11 relative to propellant container 20 and initiator chamber 10 as controlled by the spring detent 13 will determine which selected one of the lateral passages 35 will be radially aligned with a corresponding ignition hole 28, and thereby predetermine the effective length or portion of the time delay cord upon arming and firing of the initiator assembly. Arming is accomplished when safety pin 40 is removed. To fire, initiator pin 41 is pulled out of cap 11 and the firing mechanism spring 42 is compressed as balls 43 release pin 41. Impact of the firing pin on the primer 33 will ignite the uncovered pyrofuze end of cord 36.

A filter 50 is secured to the forward end of the initiator chamber and the forwardment tip is provided with a shipping cap 52. Suitable indicia means may be provided on selected portions of the assembly, such as adjacent each peripheral opening 14, that will designate the appropriate effectively or operatively aligned spool lateral passages with their corresponding propellant container ignition holes 28.

Various modifications, changes or alterations may be resorted to without departing from the scope of the invention as defined in the appended claims.

We claim:

1. In a miniature initiator assembly having an initiator chamber containing a cartridge case and propellant container,

said case being longitudinally keyed to both said chamber and container,

a spool having an open ended cylindrical portion telescopingly received between said case and container and a hub portion carrying a centrally located primer,

an initiator cap secured to said initiator chamber and rotatably mounted with respect thereto, said cap having means for rotating said spool relative to said container,

said spool cylindrical portion having an external spiral groove containing a pyrofuse cord and a plurality of spool lateral passages predeterminedly spaced along said groove, one end of said cord extending through one of said passages adjacent said primer,

said propellant container having a plurality of ignition holes predeterminedly spaced along a sidewall thereof, and

a firing pin assembly in said cap and in alignment with said primer,

so constructed as arranged that selected ones of said ignition holes can be placed in fluid communication with said cord upon relative rotation of said spool and container.

2. The structure in accordance with claim 1 wherein each propellant container ignition hole is filled with igniter mix.

3. The structure of claim 1 wherein said initiator chamber has a plurality of predeterminedly spaced peripheral recesses, and spring detent means carried by a peripheral surface of said ignition cap for engagement in a selected one of said recesses.

* i i I. 

1. In a miniature initiator assembly having an initiator chamber containing a cartridge case and propellant container, said case being longitudinally keyed to both said chamber and container, a spool having an open ended cylindrical portion telescopingly received between said case and container and a hub portion carrying a centrally located primer, an initiator cap secured to said initiator chamber and rotatably mounted with respect thereto, said cap having means for rotating said spool relative to said container, said spool cylindrical portion having an external spiral groove containing a pyrofuse cord and a plurality of spool lateral passages predeterminedly spaced along said groove, one end of said cord extending through one of said passages adjacent said primer, said propellant container having a plurality of ignition holes predeterminedly spaced along a sidewall thereof, and a firing pin assembly in said cap and in alignment with said primer, so constructed as arranged that selected ones of said ignition holes can be placed in fluid communication with said cord upon relative rotation of said spool and container.
 2. The structure in accordance with claim 1 wherein each propellant container ignition hole is filled with igniter mix.
 3. The structure of claim 1 wherein said initiator chamber has a plurality of predeterminedly spaced peripheral recesses, and spring detent means carried by a peripheral surface of said ignition cap for engagement in a selected one of said recesses. 